High‐efficiency modification of PET by the low addition of a self‐assembled functional nanocellulose film prepared from waste paper.

Polyethylene terephthalate (PET) is a conventional packaging material. Its modification has attracted immense attention in the industry and academia. Here, office waste paper, white cardboard waste, and waste corrugated paper were first employed as raw materials for cellulose nanocrystal (CNC) extraction by acid hydrolysis. Thereafter, CNC/PET composite films with various CNC additions were prepared via a self‐assembly technique. The results revealed that the CNCs formed a self‐assembled film on the PET surface via the synergistic effect of the complex interactions among the CNCs as well as between the CNCs and PET. Moreover, the CNCs improved the barrier property of PET and decreased the oxygen and water vapor transmittances of CNC/PET by 30.7% and 21.7%, respectively. Additionally, the coating of the PET surface with 0.2 wt.% CNCs extracted from the waste paper decreased the surface wettability of PET, exhibiting application potentials in the hydrophobic modification of polymers. This study realized waste paper recycling and provided a basis for constructing self‐assembled functional films on PET surfaces. The findings and insights of this study could exhibit application potentials in the fields of waste recycling and packaging materials. Highlights: A functional cellulose nanocrystal (CNC) film is prepared from waste paper.Self‐assembled CNC is coated on a PET surface to form a CNC/PET composite film.The synergistic interactions among CNCs and between CNC and PET modified PET.The low addition of CNCs realized the efficiency modification of PET.The study achieves waste paper recycling and high‐value utilization. [ABSTRACT FROM AUTHOR]